The present invention relates to efficiency optimization of integrated circuits, and more particularly to efficiency optimization that can be maintained under changing operating conditions of the integrated circuit by a servo loop.
Demand for portable electronic devices is increasing each year. Example portable electronic devices include: laptop computers, personal data assistants (PDAs), cellular telephones, and electronic pagers. Portable electronic devices place high importance on total weight of the device. The overall weight of the portable electronic device may be greatly affected by the battery. Various efforts have been made in technologies such as Lithium-Ion (Li-Ion) to provide smaller battery form factors with reduced overall weight.
The demand for higher speed circuits with smaller form factors is increasing, largely as a result of increases in the need for portable electronic devices. The density of circuits is increasing as a consequence of the need for smaller form factors such that higher power electronic devices are now placed in relatively close proximity to other circuits on a common substrate (e.g., an integrated circuit board). The increased density of the circuits results in increased heat dissipation requirements. Performance, reliability and life expectancy of electronic equipment are inversely related to the component temperature of the equipment.
Most portable electronic devices place a premium on total time of use (e.g., talk time in a cellular telephone). Batteries store a finite amount of charge that is typically rated in units of milliampere-hours (mA-Hr). Charge is depleted from the battery by the electronic device during operation. Since these devices may consume power at a rapid rate, the total time of utility (i.e., the run time of the battery) is greatly affected by power conservation techniques in the electronic device. For example, many laptop computers have power management software to extend the battery life, or conserve battery power when the battery is low. In this example, the software extends the run time of the battery by lowering the internal clock frequency of the computer.
A DC regulator such as a DCxe2x80x94DC controller is often used to control power regulation in a portable electronic device. A typical DCxe2x80x94DC controller is a buck regulator that switches current to an LC filter that provides a DC output voltage to the load. The DC output voltage is determined by the average of the voltage waveform that is delivered to the inductor, which is related to the duty cycle of the switching in the buck regulator. The efficiency of the DCxe2x80x94DC controller is rated in terms of percentage of power that is delivered to the load from the available supply (i.e., [POUT/PIN]xc3x97100%). A high efficiency DCxe2x80x94DC controller wastes very little power in the regulation process, while a low efficiency DCxe2x80x94DC controller requires more xe2x80x9coverheadxe2x80x9d that results in wasted power. For portable electronic devices, it is preferred to have high efficiency in the DC regulation process so that the run time of the battery is maximized.
This summary of the invention section is intended to introduce the reader to aspects of the invention. Particular aspects of the invention are pointed out in other sections herein below, and the invention is set forth in the appended claims, which alone demarcate its scope.
The present invention is directed to an apparatus for optimizing the efficiency of an integrated circuit with respect to at least one operating parameter. The apparatus includes a temperature sensor, a temperature change detector, and a parameter adjuster. The temperature sensor monitors a current temperature that is associated with an electronic device and provides a current temperature signal. The temperature change detector compares the current temperature signal to a previous temperature signal that was associated with the electronic device. The temperature change detector determines a direction for the temperature (e.g., increasing or decreasing). The parameter adjuster is responsive to the temperature change detector and adjusts the parameter such that a preferred operating point the electronic device is located and maintained. The preferred operating point of the electronic device corresponds to a minimum temperature of the electronic device.
In another aspect, the present invention relates to a method for efficiency optimization of an integrated circuit with respect to at least one operating parameter. The method includes steps of: initializing the parameter; monitoring a temperature that is associated with an electronic device; differentiating to determine a direction of change for the temperature; and adjusting the parameter to locate a minimum temperature of the electronic device.